In many phases of manufacturing, agriculture, service, communication, transportation, industries (as well as others) forklift trucks are commonly used and most commonly the object or objects to be moved are placed upon a pallet specifically designed to allow the tines of the forklift truck to slide into either side of the pallet. The forklift truck operator then raises the tines and moves the forklift as necessary to place the objects in the desired position.
Pallets are usually constructed of rough hardwood with slats nailed to larger wooden braces. Even when the forklift driver exercises care in operation, the momentum of the forklift and limited control results in breakage of one or more slats of a pallet rather easily. This results in limited life of a wooden pallet.
Wood for pallets is becoming scarcer and more expensive while engineering type plastics are becoming increasingly more available with enhanced engineering properties. For example, Kevlar.RTM. is five times as strong as steel on a weight basis and Nylon.RTM. and other plastics are increasingly replacing metal for gears.
The present invention is aimed at filling the need for a lower in-use cost pallet of a material primarily other than wood.
Recognizing that the normal pallet handling will result, in time, with pallet damage, the present invention covers a unique manner of fabrication of a pallet from two moldable shapes with these shapes being held rigidly connected with metal rods. The assembly is easily disassembled with hand tools so that a damaged part of the pallet may be readily replaced. Briefly the pallet which is usually about 40" by 48" is formed with six or more slats on the top side and three or more slats on the bottom side of three identical beams. The beams have depressions so that the slats fit flush with the beam surfaces. At the center of each depression is a hole with a minimum of a one square inch cross section with the hole extending through the beam. Each slat has three or more projections that fit into these holes. With slats with three projections, three beams are used and the projection location positions the beams. The projections will go more than half way through the beam. The projections are sufficiently long so that a projection on a slat used on the bottom of the pallet goes a minimum of one inch past a projection on a slat used on the top of the pallet. This is necessary to allow drilling or fabricating the beams and projections so that a rod a minimum of 1/8" in diameter may be run longitudinally through the beams and projections of the slats so that one rod through each beam securely fastens both top and bottom slats to the beams.
The design of the pallet structure as outlined allows the use of all plastic material or the substitution of either two or more slats or one or more beams of metal construction to give added strength for some special purpose pallets. In one embodiment a metallic box-like structure is fitted over the ends of the plastic beams and the first slat on top of the pallet on each end of the beams or each side of the pallet. These box-like structures are held securely fastened with nuts on threaded ends of the rods that run longitudinally through the beams to fasten the slats to the beams. Openings in the metal box-like structure may be sized to allow easy access of the forklift tines. In other embodiments the metal box-like structure is not used but the first top slat on each side is made of metal instead of plastic.
The plastic chosen will depend upon specific use of the pallet and price and properties of the plastic; for many uses Nylon.RTM., Kevlar.RTM., Delrin.RTM., high density polypropylene, high density polyethylene, fiber glass re-enforced polyester, or polycarbonates should be suitable.
The following patents have been considered:
______________________________________ Ser. No. Filing Date ______________________________________ 3,878,796 12/5/1973 4,145,976 3/27/1978 4,359,948 4/7/1980 3,857,342 6/7/1973 4,051,786 6/23/1975 3,880,092 4/29/1975 4,597,338 11/14/1984 3,835,792 10/30/1972 ______________________________________
The present invention covers a unique design to construct a pallet from only two moldable shapes with the shapes being held together with one rod slideably installed through one molded beam shape and through projections on one molded slat shape fitting closely into openings for these projections in the molded beam shapes. This unique construction allows for substitution of metal parts where special use indicates the desirability.